Mercurial > hg > blitz_stable

annotate src/org/dancres/blitz/entry/Storage.java @ 35:6f68e94c1fb8 default tip

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Add CondensedStats monitoring utility, equivalent to vmstat
author Dominic Cleal <dominic-cleal@cdo2.com>
date Thu, 05 Aug 2010 11:07:25 +0100
parents 3dc0c5604566
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
0
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
1 package org.dancres.blitz.entry;
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
2
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
3 import java.io.IOException;
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
4
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
5 import org.dancres.blitz.arc.BackingStore;
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
6
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
7 import org.dancres.blitz.mangler.MangledEntry;
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
8 import org.dancres.blitz.mangler.MangledField;
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
9
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
10 import org.dancres.blitz.oid.OID;
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
11
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
12 /**
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
13 Provides primitive methods for the manipulation of the storage mechanism.
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
14 Caching etc. is a higher-level responsibility. This interface can be
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
15 used to write, update and remove data. <P>
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
16
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
17 It has basic understanding of what it stores in that it knows how
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
18 to index, how to store subtype information and the storage patterns used
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
19 for bucketing and other settings. <P>
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
20
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
21 Basic lifecycle is to create storage element and then call didntExist.
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
22 If it returns true, one should set the indexing information using setFields.
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
23 Note that, if indexing is disabled, didntExist will always return true
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
24 and there's no requirement to call setFields. <P>
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
25 */
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
26 public interface Storage extends BackingStore {
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
27 /**
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
28 @return <code>true</code> if initialization succeeded in accordance
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
29 with the mustExist flag. i.e. If mustExist is true and the databases
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
30 couldn't be opened one will receive <code>false</code> NOT an
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
31 exception.
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
32 */
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
33 public boolean init(boolean mustExist) throws IOException;
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
34
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
35 /**
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
36 Called to setup schema information, create indexes etc - should only
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
37 be called once in response to <code>true</code> being returned from
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
38 <code>didntExist()</code>
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
39 */
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
40 public void setFields(MangledField[] aSetOfFields) throws IOException;
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
41
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
42 /**
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
43 Indicates if we were created for the first time as the result of
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
44 a call to <code>EntryRepositoryFactory.get()</code>. Note that this
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
45 flag is reset after <code>setFields()</code> is called. Thus, even
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
46 if an EntryRepository has been informed of children, it will still
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
47 return <code>true</code> until <code>setFields</code> is called.
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
48 */
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
49 public boolean noSchemaDefined();
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
50
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
51 public void close() throws IOException;
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
52
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
53 /**
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
54 Storage instances support the concepts of:
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
55
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
56 <ul>
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
57 <li> Temporarily holding Entry's in-memory only - useful for
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
58 transactional operations such as caching of writes until commit.</li>
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
59 <li> Caching of dirty data destined for disk but not yet written. This
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
60 allows for better performance as writes may be performed asynchronously.
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
61 </li>
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
62
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
63 Before a disk search is performed via <code>find</code> this method
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
64 should be invoked to check for state which may not have reached disk
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
65 as yet. If this is not done, out-of-date state may be returned.
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
66 */
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
67 public TupleLocator findCached(MangledEntry anEntry);
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
68
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
69 /**
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
70 Return a set of potential matches based on the passed template. Note
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
71 one must test each returned tuple for an exact match across ALL keys
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
72 because this method is "speculative". It will return likely matches
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
73 it does not guarentee to have located an exact subset based on the
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
74 passed template. As a full match is necessary to avoid hash-collisions
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
75 this shouldn't be a problem.
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
76
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
77 @param anEntry a template to use to locate matches.
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
78
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
79 @return TupleLocator instance of <code>null</code> if there are no
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
80 possible matches.
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
81 */
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
82 public TupleLocator find(MangledEntry anEntry) throws IOException;
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
83
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
84 /**
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
85 Tells this Repository about a subtype which has just been created
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
86 and would need to be searched if this type were the specified template.
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
87 */
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
88 public void addSubtype(String aType) throws IOException;
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
89 public String[] getSubtypes();
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
90
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
91 /**
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
92 @return a new UID for an entry to be added to storage.
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
93 */
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
94 public OID getNextId() throws IOException;
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
95
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
96 /**
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
97 Causes Storage instance to scan for expired Entry instances which will
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
98 be passed to <code>aReaper</code>
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
99 */
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
100 public void bringOutTheDead(EntryReaper aReaper) throws IOException;
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
101
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
102 /**
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
103 @return the type of Entry this storage element contains
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
104 */
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
105 public String getType();
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
106
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
107 /**
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
108 @return the number of Entry's of the type currently held on disk. Note
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
109 that because of Blitz's caching/logging behaviour, this count doesn't
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
110 reflect the actual number of instances of this type.
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
111 */
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
112 public int getNumEntries() throws IOException;
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
113
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
114 public void delete() throws IOException;
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
parents:
diff changeset
115 }